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Will Human Life Expectancy Quadruple in the Next 100 Years? 60 Gerontologists Say, "Public Debate on Life Extension Is Necessary"

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Abstract: 60 scientists in the field of biogerontology were asked to give their personal estimates regarding the development of future life expectancy. The median of these estimates is that a person born in the year 2100 will have a life expectancy of 100, the average mean is 292 years. Changes in biogerontology are discussed whereby the old search for the fountain of youth gains respectability again and competes to replace the gerontologists current mission to compress morbidity. Some anti-aging developments are discussed. It is urged that society debates these questions in order to be prepared for sudden advances that may have a large impact on society.

Just imagine that, as a result of scientific progress in the next 100 years, average life expectancy at birth (now about 75 years in the Western World) increases to 292 years! Whether you find such a perspective appealing or not, it would certainly be dramatic. In the 20th Century life expectancy roughly doubled; so what could be the justification for such an extraordinarily optimistic projection -- a quadrupling of life expectancy? It is based on telephone interviews with over 60 demographers and gerontologists -- scientists in the field of aging research -- from all over the world (who are listed in the Table below). I asked them for their personal ‘estimate’ of life expectancy (for a baby born in the year 2100). Surprisingly, very few declined to give such an estimate (though it occasionally took some convincing), and the average of these estimates turned out to be 292 years. Not a single one of these 60 academics thought that life expectancy would go down (as it apparently has in Russia, formerly the USSR), half of them thought that a year 2100 newborn would live to be at least to be 100 years old (the median is 100), while nine of them provided estimates between 200 and 5,000 years.

I personally interviewed these scientists because I didn’t know what to make of the incessant flow of press reports about alleged breakthroughs in genetics and drugs targeting specific age-related diseases. Most of these stories are so full of unsubstantiated claims that it is difficult to attain a proper perspective. So, instead of writing down all these nuances, I asked the scientists to provide me with their overall feeling for one number: average life expectancy for a baby born in 2100. This method resembles the stock market (the price of a stock reflects the confidence a collection of investors has in a company), but it is also practiced for more scientific purposes at www.foresight.org. A Dutch Professor has used this method to predict the outcome of general elections with 30 percent more accuracy and at considerably less cost than using the regular polling services.

Let’s keep our feet on the ground; no one alive today knows what life expectancy at birth will be in the year 2100. These numbers do not predict with any accuracy that a newborn in 2100 will actually become 292 years old. What it does show is that apparently many scientists expect large increases in life expectancy – and that should be taken seriously. Take for example "the greenhouse effect." Here only the threat, not a proof of a dramatic change, has convinced governments of the world that something is to be anticipated. And so we are bombarded with scientific conferences, government conferences, newspaper discussions, public campaigns, and the like. This is not so in the field of aging, and many gerontologists are unhappy about that. Prof. Dick Knook from the Dutch TNO Center for the Study of Aging says, "The discussions in government bodies are usually about increases in life expectancy on the order of months, but I frequently ask 'Suppose there is a real breakthrough?' No one is prepared for that."

A History Written by Charlatans

But the blame for this lies at least partly with the gerontologists themselves: many of them consider speculation about future life expectancy taboo. And that is understandable if one realizes that the history of this field has, for the most part, been written by quacks and charlatans who claimed to have discovered the "Fountain of Youth" -- be it in the form of monkey glands, yogurt, herbals, transcendental meditation, or the alleged lifestyle of centenarians in the Caucasus Mountains (who probably weren't even centenarians at all). Gerontologists want to be perceived as serious scientists, so they tend to avoid discussions about life extension, if they can.

As a reader, you may be surprised about the high estimates of some of the scientists in the Table below, but I have the distinct impression that many of them chose a rather low number, because they found it ‘unethical to raise false hopes.’ And besides that, they say, "there is so much suffering among geriatric patients in nursing homes today that we had better add more vitality to their final years, relieve their suffering, instead of extending that suffering by adding more years to an already decrepit life”. This concept of ‘successful aging’ and 'compression of morbidity' as it is sometimes called, has been the gerontologists' gospel for several decades. However, it has lately come under attack.

This criticism suggests that not only should scientists avoid raising false hopes but that they also have an obligation to alert society to possible dramatic changes. A quadrupling of average life expectancy to 292 years may be desirable on an individual level, but for society in general, there may be negative consequences. Dr. Aubrey de Grey from the University of Cambridge in the UK calls aging a "barbaric phenomenon that shouldn't really be tolerated in polite society," but he is very optimistic about scientific progress as can be read in his estimate that average life expectancy in 2100 will be 5,000 years. But regardless of whether that high number will ever be reached, the current trend of increasing life expectancy is very likely to go on, and public debate about this is very much needed in order to avoid potentially disruptive arguments over the ownership or legal rights to life-extension technology, if it ever were to be practical.

Dr. Shripad Tuljapurkar, of the Californian think-tank Mountain View Research, had already done a study on increasing life expectancy, but his had a 2050 time horizon. On my request, he extended this study to the year 2100 and now came up with an estimate of 130 years, which may be the most scientific estimate on my list. The ongoing genetic revolution is not included in this forecast; Tuljapurkar had no data on it. In his original report, he had severely criticized the governments of the G7-countries specifically for their bad planning of pension funds for the future. "Compared with official forecasts, we predict that in 2050, Japan will need to spend 39 percent more on the retired than they currently expect to. Our forecasts imply that even currently pessimistic projections of the costs of pensions and other costs of an aging society are underestimates."

Some scientists mentioned overpopulation as a possible negative consequence of increasing life expectancy. It wasn’t seen as a very big problem; though birth rate is more important for overpopulation than death rate – and birth rate is projected to go down in this century. It may go down even stronger possibly as aresult of increasing life expectancy. Prof. Tom Kirkwood from Newcastle University in the UK and Prof. Rudi Westendorp from Leiden University in Holland have shown that there is a strong correlation between fertility and life expectancy. If women have many children each (multiparity), their life expectation declines; conversely, if one were to live longer, one's chance of contracting fertility problems will increase.

The Concept of ‘Successful Aging’ Is Implausible

Another point of heavy debate in the world of gerontology is whether the previously-mentioned concept of ‘successful aging’ is actually plausible from a biological point of view. This concept implies that "one remains healthy until very old age and then suddenly expires in one's sleep." This may sound attractive, but according to the participants of a meeting organized at UCLA [19] it is unlikely that such will ever become a reality. The period of disease before death seems very difficult to avoid, apart from accidents, homicide, and suicide; one needs a disease to die. Dr. Judith Campisi, a well-known molecular biology and cancer researcher from the Lawrence Berkeley Laboratory said, "I know pathologists, who have told me, at autopsy, old people have cancer. They may not even know it, but they've got it."

"Having a disease but not knowing it" will be seen by some as a form of ‘successful aging,’ but more and more people may want to have their bodies diagnosed in order to find occult diseases at a stage for which they can still be cured. And apart from the technical barriers to ‘successful aging’, "it is also very far from what elderly people actually do see as desirable — the fitter they are, the more they wish to live, regardless of how old they are. Thus, public and professional policy regarding biogerontology research is in dire need of re-examination, since this policy does not presently reflect the expectations of laymen."

Dr. Aubrey de Grey proposes that, since all chronic diseases increase with age, instead of working to develop a variety of separate therapies against a myriad of age-related diseases, scientists ought to attack the process of aging itself; after all if one doesn’t age, one's chances of getting cancer or heart disease will be enormously reduced. It is not certain whether this strategy will succeed, but it is the road to be taken. However, certain respectable gerontologists have already indicated that such an approach will blur the distinction between quacks and serious scientists, like themselves. But though it is true that these modern gerontologists are now back where their science originally started, explicitly searching for the "fountain of youth" again, albeit under the more euphemistic rubric of ‘engineered negligible senescence’ (or non-detectable aging). Yet, it seems peculiar to complain that nobody will observe the difference between modern scientists (with their equipment, their journals, and critical peer review) and charlatans. Quacks, mountebanks, and charlatans will always be present, and there is no reason to avoid the questions that so many people ask themselves from time to time: "Could I live longer? or "Could I live a lot longer than the average person my age is currently expecting to live?" and if so, "What would I have to do to make it happen?"

All this is quite different from immortality. Regardless of the seemingly magical achievements of science and technology, "The Grim Reaper" will always be waiting in the wings in the form of traumatic accidents, homicides, and suicides. But according to Dr. Alexander Sidorenko, Chief of the United Nations Program on Aging, "It will also be more and more acceptable for people to make their own choice about how long they wish to live" (Designated on a medical chart as "DNR" [Do Not Resuscitate] or "No Code" ["Code Blue"}). He points to the new Dutch law on euthanasia and the debate about this in other countries. Sidorenko expects that a person born in 2100 will live to be 150 years, although he stresses that this is his own personal view.

Aging Is Not Itself a Program

Just how realistic is this speculation? According to the ‘Gompertz Law’ which dates from the 19th Century and with which one can calculate how many people in a certain society will reach a certain age, an average life expectancy of 386 years for a person born in 2100 is simply impossible when one uses current data. Dr. de Grey then argues, "In 1900, similar logic would have firmly predicted that the minimum time taken in 1950 to travel between London and New York would have to be several days"; in fact, the advent of powered flight made this estimate wrong by over an order-of-magnitude. But what developments is his and some others' enthusiasm based on?

One of the first is the discovery by Newcastle University gerontology Professor Tom Kirkwood of the Disposable-Soma Theory, which explains that aging is a by-product of Darwinian evolution (the "blind watchmaker," as it were, uninterested in consequences), and it is not supposed to make sense. Evolution has optimized our biochemical machinery for reproduction of the species; what happens after that is – from its point of view – irrelevant. It is like a house that has no more occupants: you do not maintain it anymore, and after a period of time, it collapses – a result of indifference.

More precisely, aging is not a specific program intended to slowly destroy a living being so as to create space on an otherwise overcrowded planet. In fact, there is no such thing as a single gene responsible for aging (a "death" gene, so to speak). Reasoning by contradiction, if there were such a gene then, as a result of inevitable point mutations in copying, one in an unknown number of constituents would be born without this gene and then would live forever. This subspecies being would have a reproductive advantage, and, as a result, many more immortals would be born. Since this is not the case, there is apparently no single or small group of aging genes.

Aging, then, is really an "epiphenomenon," a side effect of the fact that the program embedded in our genetic endowment for developing into an adult human being essentially runs out of new instructions. There is no new genomic programming "waiting in the wings," so to speak, like there is with a caterpillar that has yet to become a butterfly.

There are, however, several longevity-determining or "gerontic" genes that appear to make humans more resistant to wear-and-tear over time. This is apparent from an analysis of the relatives of Madame Jeanne Calment from Arles, FRANCE, who lived to the age of 122 years (and who even smoked a great deal of her life). Many of these relatives lived considerably longer than others in their time. Other studies have confirmed this, and also shown that while the chance of dying seems to increase exponentially with age, it apparently lowers slightly after [80 - 85]. When you are, for instance, 105 years old, your chance of dying is not negligible, but smaller then someone of say 79. These and other studies have suggested that lifespan is - in principle – plastic (mutable).

At the beginning of the last Century the major killers were infectious diseases like diphtheria, tuberculosis, influenza, and pneumonia, when the average life expectancy in the USA was only 49 years. At the beginning of the present Century the new killers of the post-antibiotic age, are chronic diseases, like cardiovascular disease, cancer, and stroke, when the average life expectancy has risen to 76.9 years (73 years for males and 80 years for females). Obviously, these diseases were there all along, waiting to be uncovered by the widespread elimination of infectious disease. What if these chronic diseases were also largely eliminated by medical progress in the next 50 years? Would there be a corresponding advance in average life expectancy? Apparently not, predicts Prof. Lenard Hayflick "The complete elimination of these three diseases, by whatever means, could only be expected to add just 15 years to average life expectancy." [16]

So, what are the new diseases waiting in the wings to be uncovered by the potential elimination of heart disease, cancer, and stroke? The answer is -- diseases of the "natural aging process" itself, diseases that afflict supercentenarians (those older than 110) today, who are typically blind and deaf. These diseases are characterized by "molecular infidelity," in which organelles within cells are no longer able to perform their functions, leading to the loss of tissue and organ function, and ultimately to the failure of the entire system.

What Is Going On in this Field in Practice?

In the past decade, vitamins and antioxidants have drawn considerable attention, but that seems to fade somewhat now. There is little doubt that antioxidants play a major role in our survival, but the antioxidants that our body produces naturally probably do their work so well that consuming supplements has relatively little to add for those of us who are already healthy. Their contribution, however, is not negligible though, and new antioxidants showing life-extending capabilities are constantly being developed.

"There are currently no anti-aging substances, and I should know, since I'm the Editor of The Journal of Anti-Aging Medicine," said Prof. Michael Fossel, M.D., Ph.D. from Michigan State University. Shortly after I spoke to him, I read about ALT-711 from Altheon Pharmaceuticals, which seems to come very close. This compound – which is undergoing Phase III clinical testing at present for the indication of systolic hypertension – has the ability to make blood vessels flexible and smooth again, thereby lowering blood pressure as a side effect. ALT-711 has a rejuvenating effect, since it reverses so-called "cross-linking," an age- related process whereby large molecules in blood vessels (and in the skin and elsewhere) stick together and lose their flexibility and integrity. Whether this rejuvenating effect is impressive enough remains to be seen, but there is no doubt that it's there. In other experiments, scientists have demonstrated rejuvenated immune systems in lab animals. At several universities, genetically-manipulated animals (usually fruit flies and worms) have shown considerably- extended lifespans.

It has been known since the 1930's that lab animals can live significantly longer (without signs of sluggishness or disease) if they consume a Calorically Restricted (CR) diet. At the University of Wisconsin as well as at the National Institute of Aging (NIA), primates -- the final step before human clinical trials -- are being tested, and the initial results are consistently encouraging. But although Prof. Roy Walford, M.D. UCLA Department of Pathology and dozens of other persons have practiced CR in their personal lives (and claim to feel alright), the general consensus is that this rigorous lifestyle is too onerous for the general public. And that is why other scientists are currently searching for other means to mimic the effect of CR.

These are just a few of the things that are going on, and it is hard to imagine that they will all fail. The real advances will, nevertheless, have to come from genetic modification, either before birth or thereafter. Dr de Grey's monograph [2] describes how deep within peculiar energy-producing or metabolic organelles of our cells -- the so-called mitochondria -- which resemble little "toasters," changes would have to be made in order to arrest aging altogether. Dr. de Grey also suggests various methods to excrete the undigestible pigments that remain as a side effect of metabolism. Prof. Fossel, on the other hand, suggests comparably dramatic changes in the cell’s Telomere System [4]. I believe that both approaches need to be taken seriously within the scientific community.

It is difficult to remain calm when reading about all of the experiments that are currently in progress, but we must. Despite all the fascinating developments that we read about, the fundamental question: "What specifically can I do today to increase the likelihood that I will live longer?" is still answered pretty much in the same manner as it was ten years ago [5 - 14]: (1) eat nutritiously, taking vitamin and mineral supplements every day, but try to consume fewer calories; (2) exercise regularly; (3) drink red wine moderately; (4) immediately cease all smoking; (5) remain optimistic, even in the face of adversity; (6) get married (or chose a "significant other") and maintain a wide social-support network; (7) continue your formal education; (8) limit your exposure to daily stress; and, if you can, (9) choose your parents wisely (i.e., to be long-lived). Unfortunately, however, this latter choice will no longer be available to most of us.

18. Donald B. Louria, "Second Thoughts on Extending Life-Spans: Researchers Are Making Great Strides in Extending the Boundaries of Human Aging, But the World May Not Be Ready for an End-of-Life Population Explosion," The Futurist, Vol. 36, No. 1, pp. 44-48 (January-February 2002).19. see their website at http://www.research.medsch.ucla.edu/pmts/sens/

(*) Many thanks to L. Stephen Coles for his contributions to this text